As to the problems that can been solved by genetic algorithm in Big Data, genetic algorithm research has profound significance. To meet the need of social development, many researchers have been doing a lot of work in thought and theory of that and come up with specific thought and theory. In the paper, firstly look up papers about the implementation rationale, model and specific implementation of genetic algorithm in HADOOP. Summarise two implementation models of genetic algorithm in HADOOP, vertical strategy and horizontal strategy. And deeply analyze the two implementation models, their design and implementation. Based on above, come up with improved model of genetic algorithm in HADOOP, its detailed design and general implementation steps. The improved implementation model is tested by test data to verify its correctness and validity. Experimental results prove to be that the improved implementation model of this paper is correct and valid. Finally, the improved implementation model of this paper is applied to solving facility location of emergency system.